Concentration of ores



Patented June 17, 1930 PATENT OFFICE BENJAMIN I. JOHNSON, F GARFIELD,UTAH CONCENTRATION 013 031518 No Drawing.

This invention relates to the concentration of ores, minerals and thelike by flotation, and has for its object the provision of certainimprovements in flotation processes, and more particularly the frothflotation process.

The present invention is based upon the discovery that tetrathiodiphospho organic compounds are effective flotation agents. I have foundthat these compounds, in which two 0 molecules of an organic phosphorusand sulphur containing compound are made to combine into a singlemolecule, with two phoshorus atoms bonded through two intervenmg andlinked sulphur atoms, have a marked selective action on the sulphideminerals as distinguished from gangue minerals; and when used in aflotation process, float the sulplhide minerals readily withan-attendant hig recovery of the metal values.

I have also found that smaller amounts of these tetrathio diphosphoorganic compounds are needed to produce equivalent or better results inthe flotation operation than other organic flotation agents heretoforegenerally used.

My investigations indicate that certain of the tetrathio diphosphoorganic compounds have insfiflicient frothing power to constitute acomplete agent in froth-flotation, so that an appropriate frothingagent, such as pine oil, cresylic acid or the like, may be employed inconjunction therewith, in carrying out such froth-flotation operation.

The flotation agent which is typical of these tetrathio diphosphoorganic compounds may be conveniently made by addmg diethyl dithiophosphoric acid, or its metallic salt, during continuous stirring, tostrong sulphuric acid, which must be cooled as soon as the reactioncommences, to prevent decomposition. The reaction, which continues forupwards of twenty minutes, accompanied by evolution of sulphur dioxide,may be represented as follows:

2 c o rssn B so omlmmss-ssmomom so, 211.0

The principal product of this reaction is a crystalline solid, of mildodor, which melts at 7 2-7 3 0., without decomposition or change inproperties.

Application filed October 31, i928. Serial No. mazes.

I propose to call this product tetraethyl tetrathio diphosphate,although other names may be equally appropriate. The following 1s acomparison of determined and theoretical constants of this product:

Determined Theoretinal Percent sulphur. 35. 4 Per cent phosphorus 16. 6Molecular weight 369. 85

R 0 I Rao i s R10 i mo expresses what I believe to be the constitutionso of the class of com ounds which I intend to claim for use in otation.In the general formula, R R R and B, may represent any alkyl or arylradicals or substituted derivatives thereof. The radicals maybe allalike, as in the tetraethyl compound described in detail above; or some,or all, may be different. Methyl, propyl, phenyl and "cresyl radicalsmay be mentioned, for example, as among those which can be representedby the s mbols R R R, and R above. While'I believe that the aboveformula correctly represents the reaction product of an alkyl or aryldithio phosphoric acid or its metal ic salt with an oxidizing a cut, itis understood that where I have used t is formula in the claims suchreactionproduct is indicated thereby.

Generally, these tetrathio diphospho organic compounds may be preparedthrou h the reaction of any of the organic di=th1o 1.00

phosphoric acids, or their metallic salts, with any suit-able reagentthat will effect the oxidation described. I may use any suitableoxidizing agent, such as sulphuric acid, the halogens, hypohaloids,chromic acid, dichromates or permanganates. Typical results obtained byadding these reagents to a mineral ore pulp and subjecting the resultingmixture to flotation are tabulated as follows:

Utah Copper Company mill heading ground to a fine pulp and modified withburned lime and sodium cyanide was subjected to flotation in a J anneyLaboratory machine. Gresylic acid was used at the rate of .3 ounds perton of ore and tetraethyl tetrathio diphosphate used at the rate of .05lbs. in Test 1 and at the rate of .025 lbs. in Test 2.

Heading Concentrate per cent Fe Rougher per cent Cu Rougher per centTailing per cent Fe Test Per cent Per cent Cu Fe I have found that thesetetrathio diphospho organic compounds are effective flotation agentswhen mixed with a pulp so modified as to show either acid, alkaline orneutral reaction, and the resulting mixtures subjected to flotationoperations.

I claim:

1. The improvement in the concentration of ore by froth flotation whichcomprises subjecting the ore in the form of a pulp to a froth flotationoperation in the resence of the reaction product of diethyl 'thiophosphoric acid with strong sulphuric acid.

2. The improvement in the concentration of ore by froth flotation whichcomprises subjecting the ore in the form of a pulp to a froth flotationoperation in the presence of the reaction product of a metallic salt ofdiethyl dithio phosphoric acid with strong sulphuric acid.

3. The improvement in the concentration of ore by froth flotation whichcomprises subjecting the ore in the form of a pulp to a froth flotationoperation in the presence of tetraethyl tetrathio diphosphate.

4. The improvement in the concentration of ore by froth flotation whichcomprises subjecting the ore in the form of a pulp to a froth flotationoperation in the presence of a compound represented by the formula B40in which R R R, and R stand for any alkyl or aryl organic radicals orsubstituted derivatives thereof.

